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» **Special Seminar** On the origin and evolution of galactic magnetic fields

**Special Seminar** On the origin and evolution of galactic magnetic fields

Event Details

Event Dates:

Monday, November 23, 2015 - 12:00pm

Seminar Location:

JILA 10th Floor - Foothills Room

Speaker Name(s):

Jennifer Schober

Speaker Affiliation(s):

Nordita

Seminar Type/Subject

Scientific Seminar Type:

Astrophysics Lunch Seminar

Event Details & Abstract:

Magnetic fields are omnipresent in local galaxies and influence many processes like for example star formation crucially. The proposed generation mechanisms of magnetic seed fields, however, yield strengths of typically only 10^{-20} G or below. We propose that the small-scale dynamo plays a key role in amplifying the latter up to field strengths of 10^{-5} G which are observed in galaxies today. In my talk I will introduce the theoretical basics of the turbulent small-scale dynamo and sketch our recent progress in describing it analytically and numerically. Our semi-analytical models of young galaxies show that the dynamo builds up equipartition magnetic fields by randomly stretching, twisting, and folding the field lines within only 4 to 270 Myrs. Based on these studies we expect galaxies to be strongly magnetized from early on. A test of our proposed scenario for magnetic field evolution might be possible with future radio telescopes. I will present a model for the dependency of the cosmic ray spectrum on redshift with which I predict the synchrotron emission from highly magnetized galaxies as a function of cosmic time.

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